Heretofore, in the field of liquid crystals, any mirror utilizing a liquid crystal display was used in association with polarized members. An electric current was applied to the twisted nematic liquid crystal which rotated and caused reflected light to be dimmed. Structures of this type are set forth in U.S. Pat. Nos. 3,807,831; 3,994,568; and 4,299,444. Mirrors have also been utilized in association with nematic liquid crystals as set forth in U.S. Pat. Nos. 3,612,654; 4,202,607; 3,814,501; 3,614,210 and Japanese Pat. No. 30639 (1982).
Although photocells have been utilized in association with nematic liquid crystals, they generally always use polarizers as set forth in U.S. Pat. No. 4,200,361, Japanese Pat. Nos. 149902 and 156901. Other patents utilizing photocells or photosensors include U.S. Pat. Nos. 3,862,798; 4,005,928; 4,039,803; 3,772,685; German Publication Nos. 2416172 and 2808260. U.S. Pat. No. 4,005,928 utilizes a photocell in association with a light-scattering liquid crystal material.
U.S. Pat. No. 4,021,935 relates to a flight training hood having a bistable lens system operable to a state of transparency as the pilot views the control panel of his aircraft and instantaneously operable to a state of vision occlusion respective to the pilot switching his vision to outside of the aircraft.
Heretofore, liquid crystals utilized in association with polarizers have been the standard of the industry because of their generally good contrast, wide temperature range, quick response time, and fairly good stability. Naturally, a polarizer was necessary in order to yield a contrasting color.
Generally, dichroic dyes, although known, have heretofore been utilized for digital type displays. Examples of patents containing dichroic dyes and liquid crystals include U.S. Pat. Nos. 3,643,021; 3,846,014; 3,869,195; 4,093,356; 4,114,991; and 4,266,859. Due to their general lack of good contrast, and the like, dichroic dyes are generally not used in liquid crystal displays. Examples of various dichroic dye patents include U.S. Pat. Nos. 3,900,248; 3,960,751; 4,288,147 and 4,398,805.